How To Open Mercedes Key Fob For Battery. First you need to identify which key you have. With the key still in the slot, pull the door handle.
If your buttons are worn out you may want to consider adding a silicone case to avoid further damage to your key. If the key fob appears to be working, see if the remote is transmitting a signal. If you don’t see this light, the problem is that your key fob is defective.
Look where the fob is attached to the key ring.
After the key releases, there will be a visible slot at the end of the key fob. To change the battery in your key fob, pull the latch at the end of the key holder, push your key horizontally into the open slot, and then lift the battery out of the compartment. After the key releases, there will be a visible slot at the end of the key fob. You should see a red led light, and this should appear whenever the lock, unlock, panic, or trunk button is pressed.